<?php
function output_file($Source_File, $Download_Name, $mime_type='')
{
 /*
$Source_File = path to a file to output
$Download_Name = filename that the browser will see 
$mime_type = MIME type of the file (Optional)
*/
 if(!is_readable($Source_File)) die('File not found or inaccessible!');
 
 $size = filesize($Source_File);
 $Download_Name = rawurldecode($Download_Name);
 
 /* Figure out the MIME type (if not specified) */
 $known_mime_types=array(
    "pdf" => "application/pdf",
    "csv" => "application/csv",
    "txt" => "text/plain",
    "html" => "text/html",
    "htm" => "text/html",
    "exe" => "application/octet-stream",
    "zip" => "application/zip",
    "doc" => "application/msword",
    "xls" => "application/vnd.ms-excel",
    "ppt" => "application/vnd.ms-powerpoint",
    "gif" => "image/gif",
    "png" => "image/png",
    "jpeg"=> "image/jpg",
    "jpg" =>  "image/jpg",
    "php" => "text/plain"
 );
 
 if($mime_type==''){
     $file_extension = strtolower(substr(strrchr($Source_File,"."),1));
     if(array_key_exists($file_extension, $known_mime_types)){
        $mime_type=$known_mime_types[$file_extension];
     } else {
        $mime_type="application/force-download";
     };
 };
 
 @ob_end_clean(); //off output buffering to decrease Server usage
 
 // if IE, otherwise Content-Disposition ignored
 if(ini_get('zlib.output_compression'))
  ini_set('zlib.output_compression', 'Off');
 
 header('Content-Type: ' . $mime_type);
 header('Content-Disposition: attachment; filename="'.$Download_Name.'"');
 header("Content-Transfer-Encoding: binary");
 header('Accept-Ranges: bytes');
 
 header("Cache-control: private");
 header('Pragma: private');
 header("Expires: Thu, 26 Jul 2012 05:00:00 GMT");
 
 // multipart-download and download resuming support
 if(isset($_SERVER['HTTP_RANGE']))
 {
    list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
    list($range) = explode(",",$range,2);
    list($range, $range_end) = explode("-", $range);
    $range=intval($range);
    if(!$range_end) {
        $range_end=$size-1;
    } else {
        $range_end=intval($range_end);
    }
 
    $new_length = $range_end-$range+1;
    header("HTTP/1.1 206 Partial Content");
    header("Content-Length: $new_length");
    header("Content-Range: bytes $range-$range_end/$size");
 } else {
    $new_length=$size;
    header("Content-Length: ".$size);
 }
 
 /* output the file itself */
 $chunksize = 1*(1024*1024); //you may want to change this
 $bytes_send = 0;
 if ($Source_File = fopen($Source_File, 'r'))
 {
    if(isset($_SERVER['HTTP_RANGE']))
    fseek($Source_File, $range);
 
    while(!feof($Source_File) && 
        (!connection_aborted()) && 
        ($bytes_send<$new_length)
          )
    {
        $buffer = fread($Source_File, $chunksize);
        print($buffer); //echo($buffer); // is also possible
        flush();
        $bytes_send += strlen($buffer);
    }
 fclose($Source_File);
 } else die('Error - can not open file.');
 
die();
}
?>